As a novel sweetener, sucralose is derived from sucrose by replacing the hydroxyls in the 4, 1′ and 6′ positions with chlorine. Its sweetness is 600 times of sucrose. Sucralose does not take part in human metabolism, thus has high safety and high resistance to acid hydrolysis. These advantages allow it being the most favorable highly effective sweetener, and are approved by more than thirty countries for use already. The synthetic methods of sucralose used at present may be classified into two groups, i.e. full protection methods and single group protection methods, wherein the single group protection methods are adopted by most sucralose producers, which commonly use acetyl group as the blocking group. Accordingly, in the synthesis processes of the sucralose, the last step is naturally to remove this blocking group. The prior reports such as EP0043649, U.S. Pat. No. 4,380,476, JP57046995 and U.S. Pat. No. 6,809,198 all use sodium methoxide as a catalyst to proceed the deacylation reaction. By using these methods, the reaction proceeds mildly, and the operation is relatively simple. However, the conversion ratios of these methods are low. And inorganic salts are produced during reaction, which need to be adsorbed by ion exchange resin. Furthermore, since the PH of the reaction mixture decreases during the reaction process, additional catalyst is required to be supplied.